Problem: $ C = \left[\begin{array}{rrr}0 & 1 & 1 \\ 2 & 2 & 2 \\ 2 & 1 & 2\end{array}\right]$ What is $ C^{-1}$ ?
$ = \left[\begin{array}{rrr}-1 & \frac{1}{2} & 0 \\ 0 & 1 & -1 \\ 1 & -1 & 1\end{array}\right]$